1. Field of the Invention
The present invention relates to liquid crystal display (LCD) modules, and more particularly to LCD modules having an improved structure for preventing sheets from being wrinkled. Moreover, the present invention relates to holding assemblies applied to the LCD modules.
2. Description of the Related Art
Image display devices are widely used for displaying information. Liquid crystal displays (LCD) are widely used as image display devices. For example, LCDs are widely favored as substitute for a cathode ray tube (CRT), among other reasons because they are thin, light and consumes much less power.
There is disclosed structures of the LCDs in detail in U.S. Pat. No. 5,387,922 entitled xe2x80x98Apparatus for driving an LCD module with one driving circuitxe2x80x99, U.S. Pat. No. 5,510,915 entitled xe2x80x98Out active matrix LCDxe2x80x99, U.S. Pat. No. 5,684,555 entitled xe2x80x98Liquid crystal display panelxe2x80x99, U.S. Pat. No. 5,729,316 entitled xe2x80x98Liquid crystal display modulexe2x80x99, U.S. Pat. No. 5,777,611 entitled xe2x80x98Apparatus for controlling power sequence of an LCD modulexe2x80x99 and so on.
Such a conventional LCD includes a plurality of sheets inserted between a front face of a light guide plate and an LCD panel. The sheets are, for example, diffusion sheets for diffusing light from the light guide plate and enhancing the brightness of the light, prism sheets for concentrating the light from the light guide plate and enhancing view angle, and protecting sheets for protecting the diffusing sheets and the prism sheets from being damaged.
The light guide plate and the sheets are fixed by means of fixing tape, for example, two-sided tape to be prevented from slipping out by external impacts. The light guide plate and the sheets are fixed to a mold frame by means of two-sided tape attached to the bottom of the mold frame, to stabilize the structure of the LCD module.
The technologies for fixing components by means of an adhering member such as a tape are applied to various field and disclosed in U.S. Pat. No. 5,477,779 entitled xe2x80x98Printing drum and method for attaching heat shrinkable screenxe2x80x99, U.S. Pat. No. 5,665,607 entitled xe2x80x98Method for producing thin film solar cellxe2x80x99, U.S. Pat. No. 5,620,129 entitled xe2x80x98Device and method for forming and attaching an array of conductive ballsxe2x80x99, and U.S. Pat. No. 5,477,422 entitled xe2x80x98Illuminated LCD apparatusxe2x80x99 and so on.
In the conventional LCDs, the LCD panel typically displays image information utilizing light supplied from a lamp. The lamp generates heat of high temperature as well as light. The heat generated from the lamp affects various members arranged in the mold frame, for example, the sheets, expanding the sheets to a certain degree.
Since the sheets are fixedly adhered to the mold frame by directly contacting the fixing tape, only a certain limited room is allowed for the thermal expansion of the sheets, although the sheets may expand more by the heat from the lamp.
In this case, the fixing force by the fixing tape and the expansion force by the heat create a high stress concentrated on the surfaces of the sheets.
Particularly, the sheets are very thin and accordingly more vulnerable to stress than other members. Accordingly, a little concentration of stress may seriously wrinkle the sheets.
With wrinkles, the sheets cannot perform its function to its full extent. As a result, the whole display quality of the LCD is considerably degraded.
It is therefore an object of the present invention to prevent movements of the sheets without using any fixing tape.
It is another object of the present invention to fix the sheets without any fixing tape, preventing stress concentration on the sheets.
It is still another object of the present invention to block off the stress concentration on the sheets, preventing deformation of the sheets.
It is still another object of the present invention to prevent deformation of the sheets, enhancing display performance of an LCD.
The above and other objects of the present invention will be more apparent from the following description and attached drawings.
To achieve the above and other objects, the present invention eliminates a fixing tape acting as a limitation to thermal expansion of the sheets, provides a mold frame having an improved structure and a holder to combine the sheets with the mold frame. The holder functions to exhaust electromagnetic wave and also functions to fix the sheets to the mold frame.
For example, the holder is electrically connected to an earth terminal of a printed circuit board (PCB) and a top chassis to form an electromagnetic wave exhaust passage. The electromagnetic wave output from the PCB is exhausted through the top chassis. When the sheets are inserted into the mold frame, the holder is inserted into a holding opening of the mold frame so that the sheets can be fixedly held, whereby preventing the movements of the sheets in advance. In this case, the holder simultaneously functions as the electromagnetic wave exhaust and the sheet fixing element, as aforementioned. Of course, the fixing tape for fixing the sheets is not used in this case.
A fixing projection for fixing the sheets is further formed in the holding opening of the mold frame by protruding the mold frame upwardly. In this case, the sheets are fixed by means of the fixing projection besides the holder. Accordingly, the sheets are not moved even by a strong external impact.
In addition, a pair of support projections for supporting the holder are further formed in the holding opening on both sides of the fixing projection by protruding the mold frame upwardly. In this case, the support projections prevents the holder from pressing the sheets excessively. As a result, an enough thermal expansion space for the sheets can be secured.
As aforementioned, the present invention expands the function of a PCB earth clip: the sheet holding function as well as the typical PCB grounding function. Through the expanded functions, the sheets can be appropriately fixed in the mold frame and space enough for thermal expansion of the sheets can be secured. Therefore, unexpected wrinkling of the sheets can be avoided in advance.